Ecological Risk Assessment - Glossary
of Terms

Any effect that causes harm to the normal functioning of plants or animals
due due to exposure to a substance (i.e., a chemical contaminant).

Assessment Endpoint(s):

"An explicit expression of the environmental value that is to be protected"
(U.S.
EPA 1997). In other words, what part(s) of an ecosystem should
be protected at a particular Superfund site; this is generally some characteristic(s)
of a species of plant or animal, such as reproduction, that can be described
numerically. (See Ecological
Risk Assessment Guidance Step 3 for additional information.)

Benthic community:

The group of plants and animals that live at the bottom of a pond, river,
lake, or ocean.

Benthic invertebrates:

Those animals without backbones that live on or in the sediments of a
lake, pond, river, etc.

Bioaccumulation / Bioconcentration
/ Biomagnification:

Bioaccumulation is the general term describing a process by which chemicals
are taken up by a plant or animal either directly from exposure to a contaminated
medium (soil, sediment, water) or by eating food containing the chemical.
Related terms are bioconcentration in which chemicals are absorbed
by an animal or plant to levels higher than the surrounding environment;
and biomagnification, in which chemical levels in plants or animals
increase from transfer through the food web (e.g., predators have greater
concentrations of a particular chemical than their prey).

Bioassay:

A laboratory test which determines the strength or biological effects
of a unknown or experimental substance, such as a drug, hormone or chemical;
the test is done by comparing the experimental substance's effects with
those of a known substance on a culture of living cells or a test organism.

Bioavailability:

How easily a plant or animal can take up a particular contaminant from
the environment.

Biomass:

The total mass (or weight) of plants and animals in a particular area;
can be a particular group of plants or animals or a single species. This
measurement can be used instead of counting individuals to help determine
abundances in an area.

Biomonitor:

A species that is sensitive to, and shows measurable responses to, changes
in the environment, such as changes in pollution levels.

Carnivore:

Animals that eat other animals.

Figure 1. Gray Wolf

Complete exposure pathway:

A complete exposure pathway is how a chemical can be traced, or expected
to travel, from a source to a plant or animal that can be affected by that
chemical. (See Ecological Risk
Assessment Guidance Step 3 for additional information.)

Conceptual site model:

The set of descriptions about the following topics: 1) how the different
chemicals at the site in question might affect ecological components (primarily
the plants and animals, but also the interactions among plants and animals);
2) ecosystems or ecosystem components potentially at risk; 3) the relationships
between measurement and assessment
endpoints; and 4) how plants and animals might become exposed to harmful
chemicals. (See Ecological Risk Assessment
Guidance Step 3 for additional information.)

Conservative:

A conservative risk assessment estimates high-end risk rather than low-end
risk. A conservative risk assessment should not underestimate risk and,
therefore, will indicate risk to most species of plants and animals.

Contaminant:

Any physical, chemical, biological, or radiological substance found in
air, water, soil or biological matter that has a harmful effect on plants
or animals; harmful or hazardous matter introduced into the environment.

COPEC:

Contaminant of Potential Ecological Concern; any contaminant that is
shown to pose possible ecological risk to a site. A Contaminant of Potential Ecological Concern (COPEC) or Contaminant of Potential Concern (COPC) is generally a contaminant which may or may not
be causing risk or adverse effects to the plants and
animals at a site. Contaminants of Concern (COCs) are those contaminants
which have been shown through analysis to be those that are likely to be
causing risk to the plants and animals at a site. (See
Ecological Risk Assessment Guidance Step 2.)

Ecology:

The scientific study of the relationship of organisms to each other and
to their environment.

Ecosystem:

The sum of all the living plants and animals, their interactions, and
the physical components in a particular area.

Ecotoxicity:

Toxic (harm from chemicals) effects on plants and animals, populations,
or communities.

Effects Range - Low:

The concentration of a contaminant above which harmful effects may be
expected to occur.

Effects Range - Median:

The concentration of a contaminant above which harmful effects always
or almost always occur.

ERAGS (Ecological Risk Assessment Guidance for Superfund)

Guidance describing the process for conducting Ecological Risk Assessments in the Superfund progam

Exposure:

How a biological system (i.e., ecosystem), plant, or animal comes in
contact with a chemical.

Exotoxicological Benchmarks:

Numerical values that represent concentrations of contaminants in abiotic
media (sediments, water, soil) or tissues of plants and animals above which
concentrations those contaminants are expected to cause harm. (See Screening
Benchmarks for examples.)

Habitat:

The place where a population of plants or animals and its surroundings
are located, including both living and non-living components.

Hazard Quotient:

The ratio of an exposure level by a contaminant (e.g., maximum concentration)
to a screening value selected for the risk assessment
for that substance (e.g. LOAEL or NOAEL).
If the exposure level is higher than the toxicity value, then there is the
potential for risk to the receptor. (See Ecological
Risk Assessment Guidance Step 2 for more details.)

Herbivore:

Plant-eating animal.

Figure 2. Deer

Home Range:

The undefended area in which an animal performs its daily activities:
primarily foraging, but also finding shelter, mating, etc.; this is opposed
to a territory which is defended and is generally smaller than
a home range.

In-situ tests:

Toxicity tests that involve placing plants or
animals in locations that might be affected by site contaminants and in
reference locations, rather than laboratory tests done using generic materials
and organisms. In-situ tests can provide more realistic evidence
of adverse effects than laboratory tests; however, there is little control
over many environmental factors and experimental organisms can be lost to
adverse weather or other events. Non-native species should not be used,
because of the risk of their release into the environment.

Insectivore:

Insect-eating animal.

Figure 3. Frog

Invasive/Exotic Species:

These are species that are imported from their original ecosystem. They
can out-compete native species as the invaders often do not have predators
or other factors to keep them in check. The zebra mussel is an example of
an invasive species in the Great Lakes.

Figure 4. Dragonfly, mussel, crayfish

Life-history:

The stages of life/development through which a plant or animal progresses
over the course of its life, such as larval, juvenile, adult.

LOAEL/LOAEC:

Lowest Observable Adverse Effect Level/Lowest Observable Adverse Effect
Concentration. The lowest level of a chemical stressor evaluated in a toxicity test that shows harmful effects
on a plant or animal. While LOAELs and LOAECs are similar, they are not
interchangeable. A LOAEL refers to a dose of chemical that is ingested,
while a LOAEC refers to direct exposure to a chemical (e.g., through gills
or the skin).

Measurement Endpoints and Measures
of Effect:

A measurable ecological characteristic that is related to the valued
characteristic chosen as the assessment endpoint and is a measure of biological
effects (e.g., death, reproduction, growth) of particular species, and they
can include measures of exposure as well as measures of effects. Measures
of effect often are expressed as the statistical or numerical assessment
endpoint summaries of the observations that make up the measurement.
(See Ecological Risk Assessment
Guidance Step 4 for additional information.)

NOAEL/NOAEC:

No Observed Adverse Effects Level/No Observed Adverse Effects Concentration.
The highest level of a chemical stressor in a toxicity
test that did not cause harmful effect in a plant or animal. While NOAELs
and NOAECs are similar, they are not interchangeable. A NOAEL refers to
a dose of chemical that is ingested, while a NOAEC refers to direct exposure
to a chemical (e.g., through gills or the skin).

The level of a concentration in the media (surface water, sediment, soil)
to which a plant or animal is directly exposed that is likely to cause an
adverse effect.

PEL/Probable Effects Level:

A chemical concentration in some item (dose) prey that is ingested by
an organism, which is likely to cause an adverse effect. The ingested item
is usually food, but can be soil, sediment, or surface water that is incidentally
(accidentally) ingested.

Physiology/Physiological:

(The study of) the biological processes of a plant or animal; how things
work and interact within a body, rather than just the organs and tissues
themselves.

Piscivore:

A fish-eating animal (bird, mammal, reptile, amphibian, or other fish)

Figure 5. Belted Kingfisher

Plankton:

Free-swimming (as opposed to rooted/stationary) microscopic plants (phytoplankton)
or animals (zooplankton) that live in water; they can be larval forms of
other animals such as fish or crustaceans, or adult forms of plants and
animals.

PCBs/Polychlorinated Biphenyls:

A type of organic chemical with chlorine atoms that was extensively used
in industry for a variety of purposes, but is now banned. Studies have shown
that PCBs can cause cancer in rats and possibly in humans.

Receptor:

The species, population, community, habitat, etc. that may be exposed
to contaminants.

Reference areas:

Often incorrectly referred to as a control, this is a comparatively uncontaminated
site used for comparison to contaminated sites in environmental monitoring
studies. It can be the least impacted (or unimpacted) area of the site or
a nearby site that is ecologically similar, but not affected by the contaminants
at the site under investigation.

Remediation:

Cleanup or other methods used to remove or contain a toxic spill or hazardous
materials from a Superfund site.

Risk Assessor:

The person who analyzes information from a cleanup/Superfund site to
determine if there is the possibility of harm to the local ecosystem.

Risk Manager:

The person who makes decisions concerning how to proceed with the cleanup
process in response, in part, to ecological risk studies.

A point during the Ecological Risk Assessment (ERA) process when the
risk assessor communicates results of the assessment at that stage to a
risk manager. Decisions on the next action(s) are made by the risk assessor
and risk manager.

Screening numbers (or screening benchmarks):

Levels of contaminants in particular substances (soil, sediment, water)
that are known to cause harmful effects in plants or animals. By comparing
known, maximum concentrations of contaminants at a site to screening numbers,
the possibility of ecological risk can be estimated (see Hazard
Quotients).

Sediment:

The material of the bottom of a body of water (i.e., pond, river, stream,
etc.)

A concentration in media (surface water, sediment, soil) to which a plant
or animal is exposed, above which some effect (or response) will be produced
and below which it will not.

TEL/Threshold Effects Level:

A chemical concentration in some item (dose) that is ingested by an organism,
above which some effect (or response) will be produced and below which it
will not. This item is usually food, but can also be soil, sediment,
or surface water that is incidentally (accidentally) ingested as well.

Toxicity Testing:

A type of test that studies the harmful effects of chemicals on particular
plants or animals.

Trophic Level::

This term refers to the position of a species (or in some cases, types of
species with similar feeding habitats) within a food chain or food web. For
example, in a simplified terrestrial (land-based) ecosystem, plants, which
produce their own food, are at the lowest trophic level. Above them in the
second trophic level, are herbivores such as small rodents, deer, etc. In
the third trophic level are carnivores: animals that eat other animals. In
scientific terms, an omnivore is an animal that feeds on
organisms from different trophic levels, such as a bear which eats
fish and berries.

In some cases, either due to a lack of complete information or for the sake
of simplicity and clarity, instead of specific species, a food web or food
chain will have "generic" groups, such as "small insectivorous mammals" or
"piscivorous (fish-eating) birds", reported in the different trophic levels.

Uncertainty:

A lack of knowledge about certain factors in a study which can reduce
the confidence in conclusions drawn from data in that study; it is opposed
to variability which is a result of true variation in characteristics
of the environment.